// Javi, This is like a bad dog looks like in javascript using class pattern:

// constructor
function Dog() {}

// class method 
Dog.prototype.seeCat = function() {
  console.log('seeing cat...');
  this.bark('whuf, whuf');
  this.run();
}

// class method 
Dog.prototype.bark = function(bark) {
  console.log(" U°ェ°U " + bark)
}

// class method
Dog.prototype.run = function() {
  console.log("  ε=ε=ε=ε=ε= U°ェ°U  ")
}

// constructor call
var dog = new Dog();

// executing method
dog.seeCat();